1. Field of the Invention
This invention relates to a method of and an apparatus for producing a low boiling point hydrocarbon oil from thermally decomposed or decomposed waste plastic or waste rubber.
2. Description of Related Art
Synthetic resins or plastics and synthetic rubbers have quite likely been accepted in every area for a very extensive range of applications, and are taken for granted in our modern daily lives. As a result, a considerably large amount of plastic and rubber is produced, consumed and wasted every day. Because synthetic materials do not exist as natural resources and are artificially produced, they do not decompose or disappear if only left in nature, but remain as material or physical waste in the environment. This is a problem which is being given particular attention by developed countries.
However troublesome the waste plastic products might be, in their original state, they were simply oil. Hence, it is thought that with an appropriate treatment, they might be returned to a hydrocarbon oil similar to petroleum. In this regard, rather than handling used plastic materials as wastes, they might be regarded as a resource.
In such a circumstance, with regard to recycling of a polyolefin type of plastics which are abandoned as wastes in overwhelmingly great quantities, a notable method has been proposed in, for instance, Japanese Unexamined Patent Publication 63-178195 to produce low boiling point hydrocarbon oil from the polyolefin plastics. With this method, the plastics in liquid phase are thermally decomposed and transformed into gaseous products. The resultant gaseous products are subjected to a catalytic transformation in a cell filled with zeolite which possesses specified characteristics. This method produces only a considerably reduced amount of useless wax during the process oil thermal decomposition or decomposing and provides a high yield of useful low boiling point hydrocarbon oil which is liquid at room temperatures.
However, although the wasted amount of polyolefin plastics is considerable, this is not the only type of plastics which are abandoned. Since plastic wastes generally include various types of plastics in a mixed state, it would be extremely difficult to remove only the polyolefin plastic from the others. Accordingly, the polyolefin plastic waste is treated as a mixture with other types of plastics. Such a plastic waste often includes a chlorine type of plastics, such as polyvinyl chloride and polyvinylidene chloride. When thermally decomposing or decomposing chlorine type plastics and chlorine type rubbers, a large amount of chloride compounds, such as hydrochloric acids, and chlorine gases are produced. Since these chlorine gases and chloride compounds are highly reactive, and consequently, are abundantly toxic and corrosive, not only do they corrode the equipments used for treatment, but they also have the disadvantage of corroding the zeolite catalytic material and, thereby, reducing its performance For this reason, the prior method described in the publication is unavailable to be used with plastic wastes including the chlorine type of plastics and rubbers.